Refrigeration cycle system, heat source unit, and refrigeration cycle apparatus

A refrigeration cycle system using a carbon dioxide refrigerant, comprising:

• a heat source circuit including
• a compressor,
• a heat source heat exchanger,
• a first switching mechanism that is located between a pipe through which the refrigerant discharged from the compressor flows and the heat source heat exchanger and switches a flow path, and
• a suction flow path that connects the first switching mechanism and a pipe through which the refrigerant to be sucked into the compressor flows;
• a plurality of utilization circuits respectively including utilization heat exchangers;
• a first communication flow path that connects the plurality of utilization heat exchangers and the first switching mechanism;
• a second communication flow path that connects the plurality of utilization heat exchangers and the suction flow path;
• a third communication flow path that connects the plurality of utilization heat exchangers and the heat source heat exchanger;
• a connection pipe that connects the first communication flow path and the second communication flow path;
• and
• a second switching mechanism that switches between a first state in which the first communication flow path and the second communication flow path connect and a second state in which the first communication flow path and the second communication flow path do not connect, wherein
• the second switching mechanism is a three-way valve, and
• the three-way valve does not allow the first connection point, where the second communication flow path and the connection pipe are connected, and the second connection point, where the second communication flow path and the suction flow path are connected, to connect in the first state, and allows the first connection point and the second connection point to connect in the second state.

A heat source unit of a refrigeration cycle apparatus using a carbon dioxide refrigerant, the heat source unit comprising:

• a compressor;
• a heat source heat exchanger;
• a first switching mechanism being located between a pipe through which the refrigerant discharged from the compressor flows and the heat source heat exchanger and the first switching mechanism switching a flow path;
• a suction flow path that connects the first switching mechanism and a pipe through which the refrigerant to be sucked into the compressor flows;
• a first refrigerant flow path connected to the first switching mechanism;
• a second refrigerant flow path connected to the suction flow path;
• a third refrigerant flow path connected to the heat source heat exchanger;
• a connection pipe that connects the first refrigerant flow path and the second refrigerant flow path;
• and
• a second switching mechanism that switches between a first state in which the first refrigerant flow path and the second refrigerant flow path connect and a second state in which the first refrigerant flow path and the second refrigerant flow path do not connect;
• a plurality of utilization units respectively including utilization heat exchangers;
• a first communication pipe that is connected to the first refrigerant flow path and connects the heat source unit and the plurality of utilization units;
• a second communication pipe that is connected to the second refrigerant flow path and connects the heat source unit and the plurality of utilization units;
• and
• a third communication pipe that is connected to the third refrigerant flow path and connects the heat source unit and the plurality of utilization units.